Loss of control

The aircraft was observed shortly after it had taken off towards the south-east, flying at a very low height along the beach towards the Tangalooma resort. The aircraft flew over the resort area and was seen by witnesses to perform a steep climbing manoeuvre. The aircraft then descended steeply, dived into the water whilst heading in a westerly direction away from the resort, and sank.

The aircraft appeared to be operating normally prior to the accident. There was no physiological or mechanical evidence found which may have contributed to the development of the accident. No defect was found which may have precluded normal engine operation; however, the engine appears to have not been delivering power at the time of impact.

The prevailing wind at the time of the accident was a strong south-easterly which is known to cause mechanical turbulence in the lee of the island. This may have affected the pilot's ability to recover from the manoeuvre under the circumstances.

The investigation did not reveal any reason for the unusually low flight path and manoeuvre immediately prior to the accident. The engine could not be functionally tested because of impact damage.

Significant factor

The following factor was considered relevant to the development of the accident: The pilot attempted a manoeuvre at a height from which safe recovery could not be effected.

CIRCUMSTANCES

On arrival at Sydney, the helicopter landed near the helipad and ground- taxied to the concrete apron in the general aviation parking area. The pilot intended to park in a confined space, adjacent to buildings and hangars on the north-eastern extremity of the apron. A number of aircraft were parked in close proximity to the west and south of the intended parking position. A grassed area to the east was free of obstacles. Ground marshalling assistance was not available. The surface wind was from the south-east at 10-15 kts.

The helicopter taxied to the intended parking position and stopped on an easterly heading. Witness evidence concerning the events which followed was not consistent. The pilot reported sensing a rocking motion which he interpreted as the onset of ground resonance. The helicopter was lifted off and turned towards the building. During this manoeuvre, an extreme vibration commenced which caused the pilot to experience a loss of vision and led to a loss of control of the helicopter. The passenger later recalled that the helicopter completed a 180 degree turn on the ground onto a westerly heading before the rocking motion was felt and the pilot lifted the helicopter off the ground. A ground witness seated inside the building observed the helicopter come to a halt on an easterly heading. It then became airborne and completed a hover turn left onto a westerly heading, at a height of approximately 8-10 feet. As the helicopter settled momentarily, it appeared to be rocking slightly and touched down on each wheel individually, suggesting the pilot was experiencing minor control difficulties.

The helicopter became airborne a second time and was observed to turn right onto a northerly heading, facing a building adjacent to the apron. Severe pitching oscillations commenced as the helicopter climbed to a height of about 30 ft. After several oscillations, the helicopter yawed and rolled to the left, travelling in a westerly direction towards a parked Learjet. The angle of bank increased to 90 degrees and the nose began to drop at about the time the main rotor blades struck the tailplane of the Learjet and the concrete apron. Debris was scattered over a wide area. The fuselage was propelled forward such that the nose of the helicopter collided with the closed doors of a hangar. The helicopter then impacted heavily with the apron on its left side. The tail boom separated and the extensively damaged fuselage came to rest lying on its left side, with the left engine continuing to run.

An extensive technical investigation, which was hampered by the degree of impact damage, did not reveal any evidence of a pre-existing mechanical fault or defect. The investigation was unable to positively establish the reasons for the oscillations reported by the pilot as being the onset of ground resonance, or the source of the extreme vibration which caused the pilot to lose vision and control of the helicopter. However, it was noted that the helicopter was operated in close proximity to a building in wind conditions which favoured recirculation of airflow through the main rotor disc. A possible source of vibration was the interaction of main rotor downwash and the tail rotor . It was also noted that the helicopter was taxied into a confined area where the manoeuvring options available to the pilot were limited.

SIGNIFICANT FACTORS

The following factors were considered relevant to the development of the accident:

1. The helicopter was ground-taxied to a parking position which was in close proximity to buildings and hangars.

2. The parking position and the wind conditions were conducive to the onset of main rotor recirculation.

3. The pilot reported the suspected onset of ground resonance.

4. During an attempt to recover from suspected ground resonance, an extreme vibration developed which led to the loss of control of the helicopter.

On 25 November 2009, an Ayres Corporation S2RT341 aircraft, registered VH-NZB (Figure 1), was being operated on a ferry flight from Parkes, New South Wales (NSW) to Batchelor, Northern Territory (NT), with an initial intermediate stop at Longreach, Queensland (Qld). While on final approach to Longreach, without warning, the aircraft's nose pitched upward, and an aerodynamic stall resulted. The pilot, the sole occupant, regained control and the aircraft landed safely.

A subsequent engineering investigation by the aircraft's maintenance provider determined that the elevator push rods had been fitted in the reverse order during recent maintenance, thus restricting the amount of nose down elevator travel available to the pilot.

The maintenance organisation advised the ATSB that, as a result of this occurrence, it has initiated a number of safety actions, including:

• exploring options for modifying the design of the bellcrank assembly to ensure that the push rods can only be fitted in the correct position
• ensuring that all employees are aware of their responsibilities when conducting dual maintenance inspections on flight control systems.

Preliminary report released 25 January 2010

At about 0800 Western Standard Time on 17 November 2009, the pilot of a Cessna Aircraft Company A188B Agwagon was fatally injured when his aircraft impacted terrain while conducting spraying operations near Kojonup, WA. The aircraft was destroyed.

Interim factual report released 3 December 2008

On 17 October 2007, the pilot of a Cessna Aircraft Company C210M, registered VH-WXC, was fatally injured when his aircraft impacted terrain about 257 km south-west of Warburton, WA.

The pilot had delivered an item of general freight at Warburton and was returning to Kalgoorlie when the accident occurred. The aircraft was being operated at night under the visual flight rules.

During cruise at 9,000 ft, the aircraft encountered severe turbulence, and the electrical system failed. The pilot unintentionally lost control of the aircraft when he leaned forward on the control column yoke and used both hands to search in the dark for a torch on the cockpit floor.

After recovering the hand-held torch, the pilot was able to light the instrument panel and return the aircraft to the required heading and altitude. When the battery master switch was turned off, the electrical system returned to full operation on alternators.

Maintenance personnel found that an internal electrical short in one of the 12-volt batteries had contributed to the electrical failure. After replacement of the faulty battery and completion of satisfactory electrical system checks, the aircraft was returned to service.

The pilot of the aircraft now secures his torch to his shirt with a strap to enable him to use both hands to keep control of the aircraft should a similar situation arise.

The aircraft operator now secures torches in all its aircraft with the addition of a quick release strap on the torch container.

On 20 June 2007, at approximately 0615 Western Standard Time, a Cessna Aircraft Company C208 Caravan float plane, registered VH‑NRT, departed Broome Airport, WA on a Visual Flight Rules (VFR) charter flight to Talbot Bay. On board the aircraft were the pilot and 10 passengers.

About 35 to 40 minutes into the flight, the weather conditions deteriorated, and the pilot elected to discontinue the flight and return to Broome. During the return flight, the aircraft entered an area of reduced in-flight visibility that resulted in the loss of the visual horizon.

Whilst manoeuvring the aircraft to regain visual meteorological conditions (VMC), the pilot became disoriented. The pilot made a general radio broadcast requesting assistance, which was intercepted by the crew of another aircraft who then provided advice and reassurance to the pilot. The pilot was able to regain control of the aircraft and, shortly after, resume the remainder of the flight.

The approach to Broome required the non-instrument-rated pilot to descend through cloud before becoming visual and landing.

This incident highlighted the risks of inadvertent flight into Instrument Meteorological Conditions (IMC) and of the recovery from those conditions, particularly in respect of a pilot that does not hold an instrument rating.

Aviation Safety Recommendations

[ R2007014SR029 ] [ R2007014SR030 ]

Preliminary report released 8 May 2007

On 23 February 2007, at approximately 1710 Eastern Daylight-saving Time, a Van's Aircraft Inc. RV-4 aircraft, registered VH-ZGH, took off from Essendon Airport, Victoria, with the owner-pilot and one passenger on board. The flight was to the designated Moorabbin aerobatic area over Clyde North.

At approximately 1740, witnesses reported observing the aircraft descending in a spin after completing an aerobatic manoeuvre. The aircraft engine was heard to gain power during the spin and the aircraft speed rapidly increased. The aircraft was then seen to enter into, what appeared to be, an unstable spiral dive.

At approximately 1,500 ft above the ground, witnesses reported that the engine noise was very high-pitched and loud, and objects were seen to separate from the aircraft. The rapid spiral descent continued and the aircraft was observed to impact the ground almost vertically. The aircraft was destroyed by impact forces and a post-impact fire. The pilot and passenger were fatally injured.

On 3 November 2008, a SAAB Aircraft Company 340B-229 (SAAB), registered VH-ORX, was conducting a regular public transport flight from Orange, NSW to Sydney. The crew reported that, at about 0724 Eastern Daylight-saving Time, when tracking to join a 7 NM (13 km) final for runway 34 Right (34R), a passenger sustained minor injuries following a possible wake turbulence event that resulted in a momentary loss of control of the aircraft.

Examination of the available radar, meteorological and aircraft operational data identified that the momentary upset probably resulted from wake turbulence, which was generated by an Airbus Industrie A380-800 (A380) that was conducting a parallel approach to runway 34 Left (34L). There was a 35 kt left crosswind affecting both aircraft's approaches.

Airservices Australia (Airservices) reported to the SAAB operator that, as a result of this incident, they had introduced a number of interim minor changes to Sydney parallel runway operational procedures during high crosswind conditions. Those minor changes would have effect while Airservices carried out a review of A380 operations. In addition, the Civil Aviation Safety Authority has opened a regulatory change project to review and update wake turbulence separation information in the Manual of Standards Part 172.

At 1026 Eastern Standard Time on 18 June 2008, a Robinson Helicopter Company R44 Clipper II helicopter, registered VH-RYW, departed Cairns Airport, Qld, to film a residential development site that was located in the vicinity of False Cape, about 10 km east of the airport. On board the helicopter were the pilot and three passengers.

The occupants of the helicopter reported that while conducting the second period of filming, there was a sudden and violent movement of the nose of the helicopter to the right, which continued into a rapid rotation of the helicopter. The pilot's reported attempt to reduce the rate of right yaw was unsuccessful, and he entered autorotation and attempted to reach a clear area. The helicopter subsequently collided with trees before impacting the ground, seriously injuring the pilot and front seat passenger.

This accident highlighted the risk of loss of tail rotor effectiveness associated with the conduct of aerial filming/photography and other similar flights involving high power, low forward airspeed and the action of adverse airflow on a helicopter.

The investigation also identified that the lack of the nomination of a search and rescue or scheduled reporting time for the flight, decreased the likelihood of a timely response in the case of an emergency.

In response to this accident, the helicopter manufacturer advised that it was considering a revision to the aerial survey and photography flights safety notice that was contained in the R44 Pilot's Operating Handbook. That revision would, if adopted, include a discussion of the risk of unanticipated right yaw associated with the conduct of those flights.